Making metal articles



Oct. 6, 1931. \A. KADOW 1,825,958

' MAKING METAL ARTICLES Filed Jan. 10, 1927 flagusz Kadaw Patented Oct.6, 1931 UNITED STATES PATENT OFFICE nueosr xmow, or 'roLmJ'o, oiIIo,nssrenon 'ro ran VACUUM-CASTING column-Y,

or TOLEDO, 01110, A ooaronarron or OHIO MAKING METAL ARTICLESApplication flled January 10, 1927. Serial No. 160,020.

My invention relates to metal casting,

and more particularly to metal casting where 1 the mold is exhausted forfilling purposes.

The purpose of my invention is to insure the complete filling of themold, especially where the mold cavity is comparatively narrow inproportion to its length, at least in some portions of the mold cavity.

It sometimes happens, especially. where the shape of the mold cavityrequires flowing of the metal through comparatively lon narrow passagesto reach extreme portions 0 the casting, that the metal solidifiesbefore it completely fills the casting.

The main object of the present invention is to provide a means andmethod whereby the metal is normally caused to flow beyond the extremityof the desired casting to form an extension or overcast which issubsequently trimmed off. In; this way any incompletely filled portionof the mold cavity is likely to lie beyond the limits of the castingproper.

The details of the invention will appear more clearly as the descriptionproceeds, in connection with the accompanying drawings, forminga part ofthis specification. In these drawings, Fig. 1 is an inside view of asection of a mold embodying one form of my invention; Fig. 2 is asection on the line 2-2 of Fig. 1; and Fig. 3 is a section on the, line33 of Fig. 1. I

The mold illustrated is constructed of two sections 10, 11. Acastingcavity 12 is provided between the mold sections when they arebrought together. An inlet 13 is provided at the bottom of the, mold-andthe faces of the mold sections above the casting cavity are cut away toform a vacuum chamber 14. Connected with the vacuum chamber are grooves15 around the sides of the casting cavity. The faces of the moldsections are ground away to form slit 16 between the vacuum groove andthe casting cavity. Next to the casting cavity the walls are ground awaystill further to form a space 17 into which the metal may flow beyondthe limits of the casting proper. The exact proportions of the difierentparts is immaterlal, but the slit 16 should be so narrow as to preventthe mold, while overcast space 17 at the top of entrance of metaltherein, while the space 17 should be wide enough to permit the metaltoenter.

In the preferred form of mold'there is a groove 18 running around nearthe edge of the face of one mold section, and a suitable packing 19 isprovided in this groove in order to make a tight joint between the twosections when they are brought together.

In using the device described, vacuum chamber 14 is exhausted bysuitable means 7 connected therewith through opening 20 or some othersuitable opening. The inlet 13 being connected' with suitable source ofmolten metal, the metal flows .up into the mold to replace the exhaustedair, and a casting 21 is formed in cavity 12. The metal is drawn out,not only to the extreme limits of the casting cavity, but also intospace 17 beyond the casting cavity, forming an over- 70.

cast 22, which may be trimmed ofi to complete the castin Inasmuch as anfailure to completely fi l the mold ordinarlly takes place at theextreme limits of the casting, defects will occur in the overcast'22rather 76 than in the casting proper 21, so that, when the overcast hasbeen trimmed off, the casting proper is a. perfect casting. Y

The mold illustrated is intended for casting battery grids. In such amold, incomplete filling is most likely to occur'at the sides andtop,andis more likely at the top than at the sides. Overcast s ace 17 alongthe sides insures the filling of t e side margins of the the casting.cavity is made somewhat lar er than space 17 and insures the completefilling of the top of the cavity. It is usually preferable to make theovercast space largest where it adjoins the extremity of the castlngcavitywhich is most diflicult to fill. This is usually atthe top, but incasting some forms of articles, the greatest difliculty might beexperienced in casting a lateral projection.

" It is preferable-to render the communica tion between the overcastspace andthe exhaust-in groove freest where the overcast space a joinsthe extremity of the mold most difiicult to fill. In the mold shown, airexhausted from the overcast space 17 at the 100 top of the mold does nottravel as far through slit 16 to reach the vacuum groove as air has totravel through slit 16 at the side of the mold to escape from overcastspace 17. In fact, under usual conditions, space 17 may be continued tothe vacuum groove without troublesome entrance of metal into the groove.Overcast spaces 17 at the. sides continue upward to chamber 14: at thetop. Side grooves 15 are not always necessary when packing 19 is used,or other means are employed to prevent entrance of air between the moldsections.

An leak between the mold sections allowing air to enter the mold cavityenhances the danger of defective castings by lessening the vacuum,reducing the tendency to draw metal to that portion of the mold, andfurnishing air to be trapped at that point. Packing 19 lessens thedanger of any such leaks, and vacuum grooves 15, when employed,intercept any air entering between the mold sections.

The mold shown is for forming a double battery grid, having a common barat the center. The casting cavit groove 23 for casting this central bara ords a comparatively clear path from the bottom to the top of themold, and immediately thereabove means are provided, such as raisedportion 24, to block the pamage of the metal into the vacuum groove.

It will be understood that this method of employing an overcast will beuseful with many forms of molds, and with other methods of introducingmetal, where difficulty is found is completely filling extremities ofthe mold. In such cases, by providing space for an overcast beyond theextremity of the mold which is difficult to fill, any imperfection willbe included within the overcast instead of within the casting proper.This is especially true where metal is introduced into the bottom of themold, and where air is evacuated from the space into which the metalflows to form the overcast. The overcast space provides a way of escapefor trapped air even where this space is not connected with exhaustingmeans.

It will be understood that the above specification shows and describesbut one embodiment of the invention, and that various modi fications maybe made within the scope of the appended claims.

What is claimed is:

1. A two part mold having the meeting surfaces of its parts cut away toform a casting cavity having its greatest cross-section along theparting plane, an inlet opening into the bottom of the cavity, vacuumgrooves along the sides and top of the cavity, anoverflow space outsideof the sides and top of the casting cavity, and a communicating slitbetween the vacuum groove and the overflow space.

- the 2. A two part mold having the meeting surfaces of its parts cutaway to form a casting cavity having its greatest cross-section alon theparting plane, an inlet opening into ottom of the cavity, vacuum groovesalong the sides and top of the cavity, an over ow space outside of thesides and top of the castin cavity, and a communicating slit between t evacuum groove and the overflow s ace, the overflow space along the topbeing arger than along the side.

In testimony whereof, I have hereunto signed my name to thisspecification.

AUGUST KADOW.

